Then we have a tragedy of the commons, where Pfizer and Lilly (the makers of Viagra and Cialis respectively) will wait for the other to create generic ED ads that they will both benefit from.
Also, I imagine that the cost of making and running the commercial would be pretty trivial compared to the profits to be made from the sale of the product.
The solution seems to be public awareness ad campaigns to remove the stigma surrounding talking to your GP about embarrassing conditions, while still outlawing the advertising of specific drugs.
"Got Milk?" was originally commissioned by the California Milk Processor Board, which is administered by the California Department of Food and Agriculture (i.e. the government) [1]. Also note that milk lacks much in the way of strong brand identity or distinguishing features, unlike Viagra and Cialis which are very different medications.
Also, I imagine that the cost of making and running the commercial would be pretty trivial compared to the profits to be made from the sale of the product.